In a variety of medical emergencies, the patient's life may hinge upon the ability of the physician or medical attendant to administer a particular fluid into the patient's bloodstream. In emergency situations such as on the battlefield, at traffic accident scenes or in the emergency room, the patient is often in shock, has low blood pressure, is bleeding profusely and may be thrashing about. Under such circumstances, finding and gaining access to a suitable blood vessel can be all but impossible, the resulting delay in administering drugs to the patient possibly being fatal. In the case of children or infants in any emergency, even the largest veins are so small that they may not be located. Even if located, an infant's largest available vein may be so small that stable infusion access may not be possible.
One alternative to venous access, recently reintroduced, is the intraosseous route. The medullary cavity of the long bones is composed of a rich spongy network of venous sinusoids which drain into a central venous canal. Blood then exits the venous canal by nutrient or emissary veins into the circulation. Fluids or drugs injected into the medullary area usually diffuse only a few centimeters, enter the bloodstream and reach the heart--all in only about 10 seconds from injection into the medullary cavity. It is important that any devices which provide intraosseous access have a lumen of a size adequate to allow for the infusion of relatively large volumes of fluid over a short period of time. Current intraosseous infusion procedures (meaning before the improvement described herein) utilize a hollow needle having a beveled tip and a trocar or stylet. With the stylet telescopically positioned within and extending partially out the bevelled end of the needle, the needle and trocar assembly is forceably and perpendicularly advanced against and through the desired bone until the cortex has been punctured and the needle and trocar tip has advanced into the medullary space. The trocar is then withdrawn, leaving the open end of the needle directly in the rich vascular network. Various complications, however, have made intraosseous infusion a less than ideal option. Although the needle and trocar assembly have a sharp, pointed tip, the medullary cavity may not be able to be penetrated under normal pressure. Too much force in trying to puncture the bone sometimes results in a bent needle, a broken needle, splintering of the bone, sliding off the bone and puncturing adjacent tissue or, more commonly, the needle is accidentally forced through the opposite side of the bone. Even if the needle is properly inserted into the medullary cavity, movements by the patient can easily dislodge the needle or cause it to be moved so that the end opening is occluded. These complications commonly arise in cases involving intraosseous infusion of infants and children. Additionally, fluid may leak from the puncture site into surrounding tissues. For persons older than six, the bones are too hard to successfully perform intraosseous infusion utilizing current procedures without realizing an extremely high incidence of the above complications. The current procedure has, therefore, typically been limited to children less than six years old and only after several attempts have been made to achieve venous infusion.
What is needed is an intraosseous infusion device which decreases the incidence and severity of the above described complications, which is easier to insert, which is more stable once inserted, prevents leakage of infused fluids, and, most importantly, which can be used in subjects of all ages.